Two phase distributor evaporator

ABSTRACT

A heat exchanger is provided including a plurality of parallel stacked plates defining at least one flow passage there between. A manifold having a generally hollow interior is arranged adjacent the plurality of parallel plates. An opening is disposed between adjacent stacked plates. The opening is configured to fluidly couple the hollow interior of the manifold and the at least one flow passage. A distributor assembly including an insert is disposed at least partially within the hollow interior of the manifold. The insert includes a plurality of circumferentially spaced axial flow channels and a plurality of radial connecting channels arranged in fluid communication with the axial flow channels. The radial flow channels are fluidly coupled to the at least one flow passage via the opening.

BACKGROUND

This disclosure relates generally to heat exchangers and, moreparticularly, to a heat exchanger distributor assembly and a method ofdistributing fluid to a heat exchanger.

Uniform distribution of two-phase fluid flow (liquid and gas) insideheat exchangers is difficult to achieve. In heat exchangers, such asmini-channel, microchannel, plate-fin, and brazed-plate heat exchangersfor example, distribution is particularly difficult due to therequirement that the flow be distributed among many layers and smallports. To overcome these challenges, these types of heat exchangers mayemploy a distributor having a closed-end tube with a series of holes inthe side. However, such distributors may not prevent separation of thetwo-phase fluid under different operating conditions.

SUMMARY

According to a first embodiment, a heat exchanger is provided includinga plurality of parallel stacked plates defining at least one flowpassage there between. A manifold having a generally hollow interior isarranged adjacent the plurality of parallel plates. An opening isdisposed between adjacent stacked plates. The opening is configured tofluidly couple the hollow interior of the manifold and the at least oneflow passage. A distributor assembly including an insert is disposed atleast partially within the hollow interior of the manifold. The insertincludes a plurality of circumferentially spaced axial flow channels anda plurality of radial connecting channels arranged in fluidcommunication with the axial flow channels. The radial flow channels arefluidly coupled to the at least one flow passage via the opening.

In addition to one or more of the features described above, or as analternative, in further embodiments a portion of the manifold isreceived within at least one of the plurality of plates.

In addition to one or more of the features described above, or as analternative, in further embodiments the entire manifold is receivedwithin the plurality of plates.

In addition to one or more of the features described above, or as analternative, in further embodiments an edge of the manifold is arrangedin contact with an outer edge of the plurality of plates.

In addition to one or more of the features described above, or as analternative, in further embodiments including plurality of axiallyspaced circumferential connecting channels fluidly coupling the radialconnecting channels to the at least one flow passage via the opening.

In addition to one or more of the features described above, or as analternative, in further embodiments each of the at least one flowpassages is arranged in fluid communication with the hollow interior ofthe manifold via exactly one opening.

In addition to one or more of the features described above, or as analternative, in further embodiments the opening is defined by at leastone of a ridge extending from at least one of the plurality of stackedplates defining the flow passage and a seal surrounding a portion of themanifold adjacent the flow passage fluidly coupled thereto.

In addition to one or more of the features described above, or as analternative, in further embodiments including a seal completelysurrounding the manifold adjacent the flow passage fluidly coupledthereto. The seal comprises an aperture defining the opening.

In addition to one or more of the features described above, or as analternative, in further embodiments a fluid within the distributorassembly is supplied to the plurality of axial flow channelssubstantially equally.

In addition to one or more of the features described above, or as analternative, in further embodiments the distributor assembly isconfigured to supply a fluid to each opening at a substantiallyidentical azimuthal angle.

In addition to one or more of the features described above, or as analternative, in further embodiments the distributor assembly isconfigured to supply a fluid to each opening at a different azimuthalangle.

In addition to one or more of the features described above, or as analternative, in further embodiments the distributor assembly furthercomprises a nozzle arranged upstream from the plurality of axial flowchannels, the nozzle being configured to create a homogeneousdistribution of a fluid.

In addition to one or more of the features described above, or as analternative, in further embodiments the nozzle includes a constrictionconfigured to produce a pressure drop in the fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The subject matter, which is regarded as the present disclosure, isparticularly pointed out and distinctly claimed in the claims at theconclusion of the specification. The foregoing and other features, andadvantages of the present disclosure are apparent from the followingdetailed description taken in conjunction with the accompanying drawingsin which:

FIG. 1 is an example of a conventional vapor compression system;

FIG. 2 is a exploded view of an example of a parallel flow brazed plateheat exchanger;

FIGS. 2a-2c are cross-sectional views of various manifoldconfigurations;

FIG. 3 is a cross-sectional view of a portion of the parallel flow heatexchanger of FIG. 2;

FIG. 4 is a perspective view of a distributor configured for use in amanifold of a heat exchanger according to an embodiment of the presentdisclosure;

FIG. 5 is a cross-sectional view of the distributor of FIG. 4 accordingto an embodiment of the present disclosure; and

FIG. 6 is a front view of a plate of a plate-fin heat exchanger and anadjacent distribution channel fluidly coupled thereto according toanother embodiment of the present disclosure.

The detailed description explains embodiments of the present disclosure,together with advantages and features, by way of example with referenceto the drawings.

DETAILED DESCRIPTION

Obstacles exist to the use of microchannel heat exchangers within arefrigerant system. In particular, refrigerant flow maldistribution mayoccur in the heat exchanger when a homogeneous two-phase mixture isallowed to phase separate in the manifold. For example, a vapor phase ofthe two-phase mixture has significantly different properties and issubjected to different effects of internal forces than a liquid phase.This can contribute to phase separation if the velocity of thehomogeneous two-phase mixture is reduced (e.g., as the flow area expandsentering the manifold). As a result, the flow may stratify due todeceleration in the manifold such that the flow to each passage of theheat exchanger may not be properly apportioned.

An example of a basic refrigerant system 20 is illustrated in FIG. 1 andincludes a compressor 22, condenser 24, expansion device 26, andevaporator 28. The compressor 22 compresses a fluid, such as refrigerantfor example, and delivers it downstream into a condenser 24. From thecondenser 24, the refrigerant passes through the expansion device 26into an inlet refrigerant pipe 30 leading to the evaporator 28. From theevaporator 28, the refrigerant is returned to the compressor 22 tocomplete the closed-loop refrigerant circuit.

Referring now to FIG. 2, an example of a heat exchanger 40, for exampleconfigured for use as the evaporator 28 of the system 20, is illustratedin more detail. Although described with respect to vapor compressionsystem 20, the heat exchanger 40 of the present disclosure may beconfigured for use in a plurality of other processes, such as pumpedrefrigerant loops, Rankin cycles, or other industrial heat exchangeapplications. In the illustrated, non-limiting embodiment, the heatexchanger 40 is a brazed plate heat exchanger; however, other types ofheat exchangers, such as microchannel heat exchangers and plate fin heatexchangers for example, are within the scope of the present disclosure.

As depicted, the heat exchanger 40 comprises a plurality of corrugatedplates 42 a, 42 b disposed along substantially parallel plates and beingstacked in an alternating arrangement. The plates 42 a, 42 b may be madeof stainless steel, sheet metal clad, or are otherwise coated with athin layer of braze material (not shown) that provides a joininginterface at contact points between adjacent plates 42 a, 42 b. Forassembly, plates 42 a, 42 b are temporarily clamped together and heatedto permanently braze plates 42 a, 42 b together to create alternatinglayers of a plurality of primary passages 44 and a plurality ofsecondary passages 46 between adjacent plates 42 a, 42 b. The brazingoperation hermetically seals an outer peripheral edge of the plates 42a, 42 b.

The actual design of the plates 42 a, 42 b may vary to provide aninfinite number of configurations with any number of passes and flowpatterns, such as including ridges for example. The patterns may beformed such as by stamping, etching, engraving, extruding, molding andembossing for example. As illustrated in FIG. 2, the heat exchanger 40is shown having a first fluid inlet manifold 48, a first fluid outletmanifold 50, a second fluid inlet manifold 52, and a second fluid outletmanifold 54. Each plate 42 a, 42 b includes a first fluid supply opening48 a, 48 b, a first fluid return opening 50 a, 50 b a second fluidsupply opening 52 a, 52 b and a second fluid return opening 54 a, 54 b,respectively. A seal (not shown) may surround a portion of the manifold48, 50, 52, and 54 adjacent a flow passage to form the openings 48 a, 48b, 50 a, 50 b, 52 a, 52 b, 54 a, 54 b.

Although the plurality of manifolds 48, 50, 52, and 54 illustrated inFIG. 2 are shown as being substantially encased by a portion of theplates 42 a, 42 b, other configurations where only a portion of one ormore of the manifolds 48, 50, 52, and 54 is received within plates 42 a,42 b (FIG. 2a ) or where the manifolds 48, 50, 52, and 54 are separatefrom but arranged in a fluid communication with an edge of the plates 42a, 42 b are within the scope of the disclosure FIG. 2b ). In oneembodiment, a portion of one of the manifolds 48, 50, 52, and 54 may bearranged in contact with an inner edge of one of the plurality of plates42, and arranged in contact with an outer edge of another of theplurality of plates 42. In the illustrated, non-limiting embodiment, themanifolds 48, 50, 52, and 54, comprise longitudinally elongated,generally hollow, closed end cylinders having a circular cross-section.However, manifolds having other configurations, such as a semi-circular,semi-elliptical, square, rectangular, or other cross-section forexample, are within the scope of the present disclosure. The manifoldscan extend from opposite end plates of the heat exchanger 40.

When the heat exchanger 40 is used as an evaporator in an HVAC system,such as system 20 for example, a relatively cool refrigerant enters theheat exchanger 40 through the first fluid supply openings 48 a, 48 b.Openings 48 a, deliver the refrigerant to passages 44, which conveyrefrigerant in a zig-zag or other configuration between adjacent plates42 a, 42 b to refrigerant return openings 50 a, 50 b. Openings 50 a and50 b then direct the refrigerant to outlet manifold 50 to recycle therefrigerant through the system. Similarly, a second fluid to be cooledenters the heat exchanger 40 through inlet manifold 52 and flows throughthe openings 52 a, 52 b. Openings 52 b of the heat exchanger 40 deliverthe second fluid to passages 46, which convey the second fluid in azig-zag or other configuration between adjacent plates 42 a, 42 b to thesecond fluid return openings 54 a, 54 b. As the second fluid flowsthrough passages 46, the refrigerant in the adjacent passages 44 coolsthe second fluid. After the second fluid is cooled, openings 54 a, 54 bdirect the chilled second fluid to the second fluid outlet manifold 54,where it is then provided to an environment to be conditioned.

Referring now to FIGS. 3-6 a longitudinally elongated distributorassembly 70 configured for use within the interior volume of an inletmanifold, such as refrigerant inlet manifold 48 of heat exchanger 40, isillustrated. Although illustrated within a horizontally arrangedmanifold 48, the distributor assembly 70 may also be used in any ornon-horizontal orientation (e.g., a vertical orientation). Thedistributor assembly 70 extends over at least a portion, if not theentire length of the inlet manifold 52. In addition, the distributorassembly 70 may be centered within the manifold 48, or alternatively,may be off-center, such as skewed towards a wall of the manifold 48opposite the plates 42 a, 42 b for example.

The distributor assembly 70 includes an insert 72 having across-sectional shape including, but not limited to, round, elliptical,and rectangular for example. In one embodiment, the size and shape ofthe insert 72 is generally complementary to the manifold 48. The insert72 has a plurality of distribution flow paths 74 formed therein suchthat the refrigerant provided at an inlet of the manifold 52, such asfrom line 30 of the vapor refrigerant circuit 20 for example, isdistributed substantially equally between the flow paths 74. Therefrigerant flow paths 74 extend from an internal cavity of thedistributor insert 72 to the flow passage 44 formed between adjacentheat exchanger plates 42 a, 42 b. The distribution flow paths 74 aresized to maintain the velocity of the two-phase mixture (e.g., so as tolimit phase separation) and may be any shape such as round, rectangular,oval, or any other shape for example. In addition, the distribution flowpaths 74 may take any path, such as a helical path, or a linear pathwith a metered bend for example.

By separating a two-phase mixture with a known liquid-vapor distribution(e.g., a homogeneous distribution, where no significant portions of theflow volume contain only one phase) into the plurality of distributionflow paths 74, the likelihood that the distribution of the two-phasemixture settles or redistributes (except within each flow paths 74) canbe reduced. In addition, if each of the plurality of distribution flowpaths 74 is formed having an appropriately small diameter, for examplebetween about 0.2 mm and 5 mm, redistribution of the phases of the flowis unlikely to occur because the slip between the velocity of the liquidportion and the vapor portion of the refrigerant is minimized. In anembodiment, the plurality of distribution flow paths 74 have equaldiameters (excepting for normal manufacturing variation in dies or othermanufacturing tools due to imprecision in the tool construction orwear). In another embodiment, the diameter of each flow paths 74 isselected to reduce the variation in flow resistance between differentflow circuits of the heat exchanger (to nearly match pressure dropcharacteristics of each flow path between the manifold inlet to themanifold outlet of the heat exchanger).

In the illustrated, non-limiting embodiment, each of the plurality ofdistribution flow paths 74 includes a first portion or flow channel 76extending axially over at least a portion of the length of the insert72. The axial flow channels 76 may be parallel to and circumferentiallyspaced about a central axis of the insert 72, such as in anequidistantly spaced configuration for example. As shown in FIG. 3, theplurality of axial flow channels 76 may vary in length to provide afluid flow to one or more corresponding passages 44 via refrigerantsupply openings 48 a, 48 b. Variation in the lengths of the axial flowchannels 76 may additionally be used to equalize the pressure drop ofthe fluid, and therefore the flow between the plurality of axial flowchannels 76. Alternatively, the plurality of axial flow passages 76 maybe substantially identical in length, such as extending over the fulllength of the insert 72, as shown in FIG. 5 for example.

The distribution flow paths 74 additionally include a plurality ofaxially spaced connecting channels 78, each of which is configured tofluidly couple at least one of the axial flow channels 76 to arefrigerant supply opening 48 a, 48 b and one or more of the passages 44formed between adjacent plates 42 a, 42 b. Accordingly, at least oneconnecting channel 78 is arranged in fluid communication with each ofthe plurality of axial flow channels 76. As shown in FIG. 3, each of theplurality of connecting channels 78 extends radially outward from anaxial flow channel 76 to a distribution hole 80 formed in an outersurface 82 of the insert 72. In such embodiments, the connectingchannels 78 are at least partially integrally formed with the insert 72.

One or more of the plurality of connecting channels 78 may additionallyextend at least partially around a circumference of the insert 72. Inone embodiment, the circumferential portion of the plurality ofconnecting channels 78 may be integrally formed as a portion of the heatexchanger plates 42 a, 42 b (FIG. 6). In another embodiment, thecircumferential portion of the plurality of connecting channels 78 maybe formed in one or both of the exterior surface 82 of the insert 72 andan inner surface 49 of the manifold 48. The distributor assembly 70 mayadditionally include an outer sleeve 84, as shown in FIGS. 4 and 5,arranged in an overlapping configuration with the insert 72 and beingconfigured to define a portion of the connecting channels 78 to retainfluid therein. A distributor assembly 70 having circumferentiallyextending connecting channels 78 and an outer sleeve 84 is described inmore detail in U.S. Patent Publication No. US2014/0345837, filed on May23, 2013, the entire contents of which are incorporated herein byreference.

As shown, a plurality of distribution holes 80 may be formed in eitherthe outer surface 82 of the insert 72 or in an outer sleeve 84positioned about the insert 72 and are fluidly connected to not only thedistribution flow paths 74 but also the openings 48 a, 48 b connected topassages 44. In another configuration, the plurality of distributionholes 80 may be replaced by one or more continuous slots. In embodimentshaving a plurality of distinct distribution holes 80, each distributionhole 80 may be connected to one or more corresponding connectingchannels 78. Alternatively, a plurality of distribution holes 80 may beconfigured to receive a fluid flow from a single connecting channel 78.

In the illustrated, non-limiting embodiment of FIG. 4, the distributionholes 80 are arranged along a horizontal axis such that the position ofeach hole 80 about the circumference of the housing distributor assembly70 is substantially identical. As a result, the refrigerant flow isdelivered to each of the refrigerant supply openings 48 a, 48 b at thesame azimuthal angle. In another embodiment (FIG. 3), the distributionholes 80 are positioned at different circumferential angles relative toone another.

Referring again to FIGS. 4 and 5, the distributor 70 may also include anozzle or orifice 90 arranged generally upstream from the plurality ofaxial flow channels 76. The nozzle 90 may be a separate componentpositioned adjacent an end of the insert 72, or alternatively, may belocated within a hollow region of the insert 72. In such embodiments,the nozzle 90 is fluidly coupled to line 30 of the vapor refrigerantcircuit 20 (FIG. 1) such that substantially all of the refrigerant fromthe expansion device 26 is configured to flow directly into the insert72 via the nozzle 90. The nozzle 90 includes an orifice that restrictsthe cross-sectional area of the fluid inlet path and is configured toincrease the velocity of the fluid flowing there through. Increasing thevelocity 14 advantageously provides a substantially uniform, homogeneousmixture of fluid 14. In one embodiment, the orifice of the nozzle 90comprises a venturi portion to reduce the pressure drop of the fluidpassing there through. The homogenous two-phase refrigerant mixture maybe output from the nozzle 90 in a generally conical shape and issupplied to the plurality of distribution flow paths 74 formed in theinsert 72 (see FIG. 5).

The distributor assembly 70 as disclosed herein is configured to providemore uniform distribution to a plurality of flow passages of a heatexchanger 40, particularly a heat exchanger configured as an evaporator,and even more particularly a brazed plate heat exchanger. Thishomogenized distribution will result in improved performance over awider range of flow conditions. As a result, a refrigerant system 20including the heat exchanger 40 will have an increased coefficient ofperformance and reduced power consumption.

Embodiment 1

A heat exchanger is provided including a plurality of parallel stackedplates defining at least one flow passage there between. A manifoldhaving a generally hollow interior is arranged adjacent the plurality ofparallel plates. An opening is disposed between adjacent stacked plates.The opening is configured to fluidly couple the hollow interior of themanifold and the at least one flow passage. A distributor assemblyincluding an insert is disposed at least partially within the hollowinterior of the manifold. The insert includes a plurality ofcircumferentially spaced axial flow channels and a plurality of radialconnecting channels arranged in fluid communication with the axial flowchannels. The radial flow channels are fluidly coupled to the at leastone flow passage via the opening.

Embodiment 2

The heat exchanger according to embodiment 1, wherein a portion of themanifold is received within at least one of the plurality of plates.

Embodiment 3

The heat exchanger according to either embodiment 1 or 2, wherein theentire manifold is received within the plurality of plates.

Embodiment 4

The heat exchanger according to either embodiment 1 or 2, wherein anedge of the manifold is arranged in contact with an outer edge of theplurality of plates.

Embodiment 5

The heat exchanger according to any of the preceding embodiments,further comprising a plurality of axially spaced circumferentialconnecting channels fluidly coupling the radial connecting channels tothe at least one flow passage via the opening.

Embodiment 6

The heat exchanger according to any of the preceding embodiments,wherein each of the at least one flow passages is arranged in fluidcommunication with the hollow interior of the manifold via exactly oneopening.

Embodiment 7

The heat exchanger according to any of the preceding embodiments,wherein the opening is defined by at least one of a ridge extending fromat least one of the plurality of stacked plates defining the flowpassage and a seal surrounding a portion of the manifold adjacent theflow passage fluidly coupled thereto.

Embodiment 8

The heat exchanger of any of embodiments 1-6, comprising a sealcompletely surrounding the manifold adjacent the flow passage fluidlycoupled thereto, and wherein the seal comprises an aperture defining theopening.

Embodiment 9

The heat exchanger according to any of the preceding embodiments,wherein a fluid within the distributor assembly is supplied to theplurality of axial flow channels substantially equally.

Embodiment 10

The heat exchanger according to any of the preceding embodiments,wherein the distributor assembly is configured to supply a fluid to eachopening at a substantially identical azimuthal angle.

Embodiment 11

The heat exchanger according to any of the preceding embodiments,wherein the distributor assembly is configured to supply a fluid to eachopening at a different azimuthal angle.

Embodiment 12

The heat exchanger according to any of the preceding embodiments,wherein the distributor assembly further comprises a nozzle arrangedupstream from the plurality of axial flow channels, the nozzle beingconfigured to create a homogeneous distribution of a fluid.

Embodiment 13

The distributor according to embodiment 11, wherein the nozzle includesa constriction configured to produce a pressure drop in the fluid.

While the present disclosure has been particularly shown and describedwith reference to the exemplary embodiments as illustrated in thedrawing, it will be recognized by those skilled in the art that variousmodifications may be made without departing from the spirit and scope ofthe present disclosure. Therefore, it is intended that the presentdisclosure not be limited to the particular embodiment(s) disclosed as,but that the disclosure will include all embodiments falling within thescope of the appended claims.

1. A heat exchanger, comprising: a plurality of parallel stacked platesdefining at least one flow passage there between; a manifold arrangedadjacent the plurality of parallel plates, the manifold having agenerally hollow interior; an opening disposed between adjacent stackedplates, the opening being configured to fluidly couple the hollowinterior of the manifold and the at least one flow passage; and adistributor assembly including an insert disposed at least partiallywithin the hollow interior of the manifold, the insert including aplurality of circumferentially spaced axial flow channels and aplurality of radial connecting channels arranged in fluid communicationwith the axial flow channels, the radial flow channels being fluidlycoupled to the at least one flow passage via the opening.
 2. The heatexchanger according to claim 1, wherein a portion of the manifold isreceived within at least one of the plurality of plates.
 3. The heatexchanger according to claim 1, wherein the entire manifold is receivedwithin the plurality of plates.
 4. The heat exchanger according to claim1, wherein an edge of the manifold is arranged in contact with an outeredge of the plurality of plates.
 5. The heat exchanger according toclaim 1, further comprising a plurality of axially spacedcircumferential connecting channels fluidly coupling the radialconnecting channels to the at least one flow passage via the opening. 6.The heat exchanger according to claim 1, wherein each of the at leastone flow passages is arranged in fluid communication with the hollowinterior of the manifold via exactly one opening.
 7. The heat exchangeraccording to claim 1, wherein the opening is defined by at least one ofa ridge extending from at least one of the plurality of stacked platesdefining the flow passage and a seal surrounding a portion of themanifold adjacent the flow passage fluidly coupled thereto.
 8. The heatexchanger of claim 1, comprising a seal completely surrounding themanifold adjacent the flow passage fluidly coupled thereto, and whereinthe seal comprises an aperture defining the opening.
 9. The heatexchanger according to claim 1, wherein a fluid within the distributorassembly is supplied to the plurality of axial flow channelssubstantially equally.
 10. The heat exchanger according to claim 1,wherein the distributor assembly is configured to supply a fluid to eachopening at a substantially identical azimuthal angle.
 11. The heatexchanger according to claim 1, wherein the distributor assembly isconfigured to supply a fluid to each opening at a different azimuthalangle.
 12. The heat exchanger according to claim 1, wherein thedistributor assembly further comprises a nozzle arranged upstream fromthe plurality of axial flow channels, the nozzle being configured tocreate a homogeneous distribution of a fluid.
 13. The distributoraccording to claim 11, wherein the nozzle includes a constrictionconfigured to produce a pressure drop in the fluid.